Method of testing a nozzle connection

Abstract

A nozzle testing method involves testing a nozzle connection via pressurized fluid. The nozzle is subjected to both circumferential and axial tension the magnitude of which is approximately equal to that achieved in a full system pressure test. The method isolates and pressure tests a nozzle in a vessel or pipe by using a device that is inserted from the outside of the nozzle to be tested, although for some applications a restraining head may be placed from the inside of the vessel. The test devices supporting the method are capable of reacting the axial pressure thrust force with a structural member or fluid pressure bearing on the external surface of a vessel or alternatively internal to the vessel or pipe bearing on the opposite wall of the pipe or vessel. The stresses applied to the nozzle neck and attaching weld are primary stresses due to the applied pressure.

1 . A nozzle testing method, the nozzle testing method comprising the steps of:
 internally pressurizing a nozzle with a test pressure (P), the nozzle having a nozzle neck, the nozzle neck having an inside nozzle diameter (D) and a nozzle neck thickness (t);   subjecting the nozzle neck to a primary membrane circumferential stress;   subjecting the nozzle neck to a primary membrane axial pressure thrust force; and   reacting the axial pressure thrust force by a vessel shell, the vessel shell being welded to the nozzle neck.   
   
   
       2 . The method of  claim 1  wherein the primary membrane circumferential stress is approximately equal to (P)(D)/(2t). 
   
   
       3 . The method of  claim 2  wherein the primary membrane axial pressure thrust force is approximately equal to (P)(π/4)(D 2 ). 
   
   
       4 . The method of  claim 1  wherein the primary membrane circumferential hoop stress is independently controlled relative to the primary membrane axial pressure thrust force. 
   
   
       5 . The method of  claim 1  wherein the step of internally pressurizing the nozzle with a test pressure (P) is performed via an expansion joint bellows construction. 
   
   
       6 . The method of  claim 1  comprising the steps of simultaneously providing minimal axial restraint while maintaining a pressure seal. 
   
   
       7 . The method of  claim 1  comprising the step of restraining the test pressure via a sealed pressure thrust restraining head. 
   
   
       8 . The method of  claim 7  wherein the sealed pressure thrust restraining head is preloaded 
   
   
       9 . A method of testing a nozzle, the method comprising the steps of:
 pressurizing a nozzle with an internal test pressure (P), the nozzle having a nozzle neck with an inside nozzle diameter (D) and a nozzle neck thickness (t);   subjecting the nozzle neck to a circumferential stress;   subjecting the nozzle neck to an axial pressure thrust force; and   reacting the axial pressure thrust force via a vessel shell attached to the nozzle neck.   
   
   
       10 . The method of  claim 9  wherein the circumferential stress is approximately equal to (P)(D)/(2t). 
   
   
       11 . The method of  claim 10  wherein the axial pressure thrust force is approximately equal to (P)(π/4)(D 2 ). 
   
   
       12 . The method of  claim 9  wherein the circumferential stress is independently controlled relative to the axial pressure thrust force. 
   
   
       13 . The method of  claim 9  wherein the step of pressurizing the nozzle with an internal test pressure (P) is bellows controlled. 
   
   
       14 . The method of  claim 9  comprising the step of restraining the test pressure via a sealed pressure thrust restraining head. 
   
   
       15 . The method of  claim 14  wherein the sealed pressure thrust restraining head is preloaded. 
   
   
       16 . A method of testing nozzle neck connection, the method comprising the steps of:
 internally pressurizing a nozzle neck with a test pressure;   circumferentially and axially stressing the nozzle neck via the test pressure; and   reacting the axially stressed nozzle neck via a vessel shell connected to the nozzle neck.   
   
   
       17 . The method of  claim 16  comprising the step of independently controlling the circumferentially and axially stressed nozzle neck. 
   
   
       18 . The method of  claim 16  wherein the step of internally pressurizing the nozzle neck is bellows controlled. 
   
   
       19 . The method of  claim 16  comprising the step of restraining the test pressure via a sealed restraining head. 
   
   
       20 . The method of  claim 19  wherein the sealed restraining head is preloaded.